Container Gardening 101

The following 101, on container gardening, comes from a federal civil servant turned home brewer, food grower, and putter upper (not to mention HOMEGROWN member), Dr. John. John has been gardening in the ground and in containers for the past 20 years. He also developed Bucket Brigades (bucket-sized salad gardens for those in need); he has helped high school FFA clubs with container gardening and simple hydroponics fundraising projects; and he founded the food-security organization Aiken Localvore. Thanks so much for lending your know-how, John, and please keep the good ideas growing!

Container gardening is just like any gardening endeavor: You’re constantly learning. Each season is different, and the plants, well, they’re plants. They don’t always do what you want or expect them to do. That said, you’re the keeper of the flock—or, in this case, the flower box, window box, or herb pot—and your time is essential to creating a successful container. (Not a lot of time, but still.) My best advice? Keep it fun and simple! If it’s not fun and becomes another job, you’ll stop doing it, and your investment will go to waste. And nobody wants waste, right?

A couple of notes before we start: In this 101, we’ll cover small containers, such as clay pots, fancypants planters (GrowBoxes, EarthBoxes, et cetera), and DIY boxes of all stripes (tried-and-true window boxes, EarthTainers, and beyond). If you’re looking for help on building and gardening in raised beds, never fear. There’s a 101 for that. Now let’s dig in!

DECIDING WHAT TO GROW

Herbs, strawberries, and flowers are common container plants, but many vegetables grow well in containers, too. Think tomatoes (especially determinate varieties, though if you’re an assertive pruner, don’t be afraid of indeterminates), peppers, radishes, carrots, and lettuce. Heftier produce, including potatoes and beans, can be grown in clean trash cans from the dollar store, recycled wash tubs, buckets, or barrels. HOMEGROWN member Chris even keeps a mango tree in a container. You get the idea. (HOMEGROWN note: We’re looking for someone to write a Potato Tower 101. Are you a tower pro? Give us a yell!We need you!)

Don’t have a lot of space? You can always go vertical. You might think vines like cucumbers, squashes, and melons wouldn’t grow in containers, since they reach out from their source and spread across the open ground or garden bed. Right? Wrong! You can redirect the growth from horizontal to vertical using any type of surface that gives the vine something to cling to. You may already be doing this with tomatoes and beans without even thinking of it as such. Lots of things can work as a support structure, from a discarded tomato cage to a paint-free trellis, from stakes laced with chicken wire to heavy duty twine, even the rails of a deck or balcony. There’s a lot more space out than there is up! (Bonus: A 101 on vertical gardening is in the works.)

Not to squash your hopes now that we’ve raised them like, well, squash on a vertical vine, but don’t be discouraged if you don’t end up with massive harvests. Regardless of the plants you select or the direction you grow them in, you won’t get the same size yield with container gardening as you would growing in ground. That’s not the intent. But if you’re an attentive container gardener, you will get edibles—and you will learn by leaps and bounds.

CROP-SPECIFIC TIPS FOR CONTAINERS

Got plant-specific suggestions on growing in containers? (Are onions worth the work? How can you tell if container-grown tomatoes are getting enough, or too much, water?) Post them in the comments section below, and we'll incorporate them into the 101. Thanks, y'all!

CHOOSING CONTAINERS

The beauty of container gardening is that almost any type of container can be suitable. Don’t get hung up on what to use. Stay focused on three elements: your intent for the garden (food? flowers? herbs?), watering, and proper drainage. That last one is important. You need to make sure that water can drain from whatever container you choose. You want a container with holes or a container that you can poke holes into, as well as a saucer for the water to drain into. A word to apartment and condo dwellers gardening on decks: Your downstairs neighbors will appreciate the saucers, even if you don’t think they're necessary.

Why is drainage so important? If water can’t drain out of your container, you can end up with rotting roots—in other words, game over. A related tip, from HOMEGROWN member Chris: “Containers that incorporate a cistern in the bottom, for holding a reserve supply of water and wicking it automatically to the roots, are the best in my opinion. With those types of containers though, you want to avoid using any potting soil labeled ‘moisture control,’ as that's formulated for regular pots and can cause root rot.”

Another consideration when choosing containers is size. You want to find containers that are small enough in width that you can comfortably reach over and around them.

But you don’t have to spend a fortune looking for perfectly sized pots: Recycle and salvage used containers! I can’t stress this enough. If it meets the three elements—intent, watering, drainage—then reuse it! Better Homes and Gardens has a nice page on this topic. The only caveat: Make sure the container will not leech toxins into your soil and your plants.

One recyclable item I've found that makes a really nice planter is a damaged wicker tote, similar to those you can find—intact, that is—at a home-goods store. (Don't ask how I damaged it. Just accept the fact that wicker and a hot burner don't mix. It smells really good, though, like a fireplace or a smoker.) These decorative baskets look nice filled with edibles or flowers in a room or on a deck or a porch.

It meets the three requirements—intent, watering, and drainage (very porous but not leaky)—so why not? Just find a large wicker basket or tote.I used a 13.5" x 8.5" x 6" version and paid about $2.50 for it. Line the basket with a garbage bag. I needed the lining to keep the dirt in since I burnt a 1-inch hole in the bottom, but the liner also gives you a water barrier. You can bring the liner an inch or two up the sides of the basket; the rest of the basket will permit evaporation and air circulation. Place your plant and fill with potting mix, as usual. I found the basket's built-in handles especially useful, and the wicker weighs almost nothing compared to large clay and ceramic pots. Bonus: These make great gifts!

If you’re reading this 101, you may already have a pretty good idea where you’re going to place your container garden. So, let’s confirm your thoughts. The most important question is: Why are you growing this garden? To supplement your food supply? To grow some cutable flowers? To create an at-home herb farm? Your intent will determine the type and number of plants you’ll need, which in term dictates the size and type of containers you’ll want, which in turn determines the amount of space you need. I promise to keep the math to a minimum, but:

why = plant type/number = container size/type = space required

The key considerations when choosing where to put your plants: your ability to access them (don’t stick your pots somewhere—a high window ledge, maybe—where you won’t be able to reach their yield come harvest time), available space, your own physical ability (Can you really lift 60 pounds? Really?), and legal use of the space.

To that last point, if you’re an apartment or condo dweller (i.e., folks who frequently choose container gardening), you can’t block the landing or the stairs of a fire escape, and you can’t introduce a hazard by overloading a balcony with heavy containers. Instead, take a look at what you have to work with and go from there. If you have windows, how about using brackets that mount on the frame or deck rail and install a box there? Or if you have no outdoor space to speak of, set a small metal or wood TV dinner–style table near your windows and pile it with containers of various sizes. (HOMEGROWN note: We’re actively recruiting folks to write window farming and indoor gardening 101s. Got insight to share? Drop us a note and volunteer!)

Regarding another key consideration, light: For most edibles, direct sunlight for at least 6 to 8 hours per day is a minimum. If in doubt, read the instructions that came with your seeds or seedlings, or refer to a seed catalog.

As for the heft question: One gallon of water weighs approximately 8 pounds. Each GrowBox I use holds 4 gallons, or 32 pounds, of water. Factor in the weight of the potting mix at about 8 pounds, and you’ve got a total weight of 50 pounds per box, without any handles to lift it with. This is truly dead weight. I’m not calling you weak. I’m just saying.

Other obstacles to look out for: animals on the prowl, falling objects, and torrential runoff from the roof, gutters, the sky, or upstairs neighbors who, when watering their own plants, might wash out your containers.

And one last word on location before we move on: Out of sight, out of mind. The closer the containers are to your door, the more attention you’ll give them and the better your yield. I like the idea of frequently passing by my containers as if I’m checking on my children.

WHAT'S THE DIFFERENCE BETWEEN POTTING SOIL AND POTTING MIX?

Let's clear up a major question right here: What's the difference between "potting soil" and "potting mix" (also called soilless mix)? Potting soil may have amendments in it (perlite, vermiculite, et cetera) but first and foremost: IT CONTAINS ACTUAL SOIL. Because potting soil can be dense and heavy, it can stay water logged, leading to root rot and restricted airflow. It's generally better for raised beds or in-ground planting than for container gardening. That said, a megathirsty plant that drinks a lot of water will like potting soil.

Potting mix, also called soilless mix, is made up of things like perlite, vermiculite, possibly peat, possibly sphagnum moss, or possibly coir, but IT DOES NOT CONTAIN SOIL. Potting mix is especially popular as a growing medium for starting seeds. It drains well and allows airflow while still retaining water, which makes it ideal for small container gardening. That said, it's not always black and white, and an experienced home gardener is nothing if not a chemist, mixing and remixing his or her formula per season and per plant. (More on recommendations for those below.)

This year I used a commercial potting mix with a built-in fertilizer that will release its nutrients over the course of three months or so. (FYI: If you use potting mix that includes a fertilizer, you don’t need to add additional fertilizer. You can order the GrowBoxes, for example, with a bag of Jobe’s organic fertilizer included—enough for one box.

Whatever fertilizer you use, be sure it’s organic. Why not chemical fertilizers? With organic fertilizers, you’re not adding chemicals or pesticides that are harmful to your plants or to us humans who eat their crops. Plus, most organic fertilizers release their nutrients over time, while chemical types tend to dump their nutrients all at once, requiring additional feedings.

So, what counts as an “organic” fertilizer? First choice: Compost! You can add it to your soil or you can use 100 percent compost as your growing medium. For how to start your own compost pile, check out the Composting 101. (For other soil supplements, also see the Seaweed and Raising Rabbits 101s.) For soil mixes, take a look at the recommended formulas below, courtesy of this downloadable PDF from the University of Maryland:

» 1 part coir (AKA coconut-husk matting, made from minced-up coconuts and a lot eco-friendlier than peat; you can find it at most garden centers)

Chris recommends adding a layer of garden lime a few inches from the top of your container, especially for acidic plants like tomatoes. “You want to use dolomite lime or agricultural lime, but not hydrated lime,” he says. “Whenever you buy an EarthBox, it comes with a bag of potting mix, a small bag of vegetable fertilizer, and a small bag of dolomite. That's what threw me years ago, as I had never heard of dolomite. I figured it was some kind of exotic stuff harvested on a distant mountain, so I kept buying the replant kits from the company. It wasn't until I found Ray's plans [HOMEGROWN note: “Ray’s plans” are for the EarthTainer, a build-it-yourself project, despite its trademarked-sounding name, of which both Chris and John are fans] that I realized everything I needed to build and fill my own containers could be found at Lowe's.”

How do you decide what kind of supplements your soil needs? Check out Rachel’s excellent Soil Testing 101. If, however, you’re going the straight-outta-the-bag potting soil route, one 2.1-liter bag of potting soil will fill approximately three 14-quart containers; half a bag will nearly fill one GrowBox, and one-quarter of a bag will fill a City Planter box. I prefer to leave about 2 to 3 inches at the top of the container for ease of watering, even though most instructions say to fill to the brim with soil.

WATERING YOUR CONTAINERS

Speaking of watering, smaller containers, such as window boxes and clay pots, dry out much faster than plants planted directly in the ground—or even in raised beds—and require more attention to watering. Moisture-control potting mixes and coir, mentioned above, help retain moisture in your container. Not sure how much to water? The plant will tell you what it needs. Early on, in cool weather, every other day might be fine. Mature plants in hotter weather probably will require daily watering.

Let me repeat one thing here, from experience: Be careful of roof runoff! I picked a location for my containers with sunlight as my key priority, not thinking about overhead runoff from my roof deck. We had some nice spring showers this past weekend, and at first the plants were doing just fine. Then I went out to look at the containers today and saw that one was flooded with water. The potting mix looked like quicksand, and the drain holes were plugged. The tomato plants were floating like buoys in the bay, the Thai peppers were underwater, and the leeks? They were leaked!

The container was nothing but South Carolina marshland. Now, in all fairness, I didn’t cover the container, as instructed. Even covered, though, it wouldn’t have provided much protection against the torrents. We emptied the marsh into our other garden, refilled the box with the remaining potting soil mixture, covered the box with an empty bag, cut a few slits in the bag, and replanted the tomato and pepper plants. Lesson learned.

• Whether you’re a newbie at container gardening or an old hand, you might consider joining HOMEGROWN’s Urban Gardeners group, where you can post nitty-gritty questions and share ideas.

THE BEST FROM THE REST OF THE WEB

Don’t be overwhelmed. Container gardening is growing in pots. It's that simple. You can do it! But if you’d like a little more help:

• One resource mentioned above that John especially likes is engineer Ray Newstead’s EarthTainer Construction Guide. Newstead walks you through the whole process, from making your own container to mixing fertilizer to selecting plants. Bonus: more on self-watering containers.

• Also from Mother Earth News, a how-to here and another here on making your own organic fertilizer.

• John also likes this PDF from the University of Maryland Cooperative, which provides a simplified process for beginner container gardening, as well as this PDF from Iowa State addressing pot sizes, potting mix recipes, and suggestions for what to grow.

Got a question about container gardening? Another tip to share? Post a comment below and keep the conversation rolling! In addition to the links above, you can find all kinds of other things to plant, grow, cook, preserve, make, craft, and pot in the HOMEGROWN 101 library.

Replies to This Discussion

Great resources! I'm looking for some tomato-specific information, so I would definitely add the following sites to the 101 resource list. I want to know 1) best conditions for container tomato gardens 2) best varieties to plant in containers 3) predicting and preventing pest and disease issues. I found some answers from these sites:

As an avid container gardener (not always successful, but really enthusiastic), I'm happy to find articles on the subject. Thanks for an inspiring read!

Right now, if I just tally what my morning groggy brain allows me, we're growing two different heirloom tomatoes, sweet red peppers, snap peas, carrots, onions, garlic, beets, two varieties of English lavender, roses, cilantro, parsley, sage, spinach, lettuce mix, Yukon gold potatoes, and an assortment of non-edible ornamentals. Oh, and blueberries, strawberries, and two vines of Chardonnay, that all survived the winter. We can't wait to get a house so we can start a bigger garden. :)

Here is a current photo taken today of the container garden. I had to move it due to house construction. The tomatoes - both in the patio box and the garden box, are so heavy with tomatoes I'm running out of supports. The patio box has over 14 tomatoes on the patio/container determinate tomato plants, and the indeterminate big boys and others are blooming their heads off with core stalks the size of my thumb. the heirlooms (in the front) are twice the size they were last week. Anybody in the "putting up section" of homegrown want to help me with what to do with these veggies??? Me thinks I will have a good crop of tomatoes, cabbage, melons and cucs all summer.

PVC pipe may be used to create a vertical container garden outdoors and indoors (24/7/365). My charity, NPI, has developed, tested and posted a guide on this subject under the title "Healthy Foods Handbook," shown on NPI's website (www.needfulprovision.org), 3rd topic on the upper left. The information is free.